1. Field of the Invention
The present invention relates to a self-driving closure device for driving a closure member, such as a window glass of a automobile or a sun-roof panel, in order to open and close the window or the roof opening. More particularly, it relates to a self-driving closure device in which the driving power source is carried by the closure member so as to move as a unit therewith.
2. Description of the Prior Art
A self-driving power window regulator, which has become popular in recent years, for use on, for example, passenger cars, will be described as an example of the conventional self-driving closure device.
Such self-driving power windows are disclosed, for example, in Japanese Utility Model Laid Open Publication No. 60-68284 and Japanese Patent Laid-Open No. 61-286485. The self-driving power windows shown in Japanese Utility Model Laid-Open Publication No. 60-68284 will be described by way of example.
As shown in FIG. 24, the power window regulator shown in the above-mentioned Utility Model has a glass holder 12 fixed to the lower end of the window glass 10, a reversible motor 14 fixed to the glass holder 12, a pinion gear 18 which is driven by the motor 14 through a worm gear 16, and a rack 20 which is fixed to an inner panel of a door so as to extend vertically and mesh with the pinion 18.
This power window regulator is advantageous in that the number of parts employed is reduced by virtue of the fact that the window glass is driven by the engagement between the stationary rack 20 and the pinion 18 which is carried by the window glass itself.
In the self-driving power window regulator described above, the motor 14, as the driving power source for opening and closing the power window, moves together with the window glass 10 which is the closure member to be driven.
Usually, the path of movement of the window glass 10 is determined by guides which are disposed inside the outer door panel. On the other hand, the motor 14 is required to move in such a manner that the pinion 18 is always maintained in meshing engagement with the rack 20. It is therefore necessary that the motor 14 is moved along the rack 20.
In general, however, a play more or less exists between the window glass 10 and the door guide. It is quite difficult to obtain a high degree of conformity between the paths of the window glass 10 and the pinion because of errors such as those incurred during the mounting of the guides which determine the path of movement of the window glass and the rack 20, dimensional error that is incurred during the fabrication of these parts, and so forth.
In the event that one or both of these paths have been offset from the correct position, the pinion and the rack cannot correctly mesh with each other resulting in impaired smooth driving. In addition, load on the pinion and the rack, as well as the load acting on a rubber cushion of the window, is increased undesirably.
In order to obtain a self-driving power window regulator of the type described, it is necessary to enhance the dimensional precision of the parts, as well as the precision of mounting the rack 20. In consequence, cost is increased and the assembly work is extremely complicated. For these reasons, a self-driving power window regulator of the type described cannot be satisfactorily put into practical use.